1. Field
The following description relates to a an apparatus to drive a light emitting diode (LED), and more particularly, to an LED driver apparatus enabled to detect whether LED arrays are connected to output ports to drive the LED arrays.
2. Description of the Related Art
A liquid crystal display (LCD) is widely used to display arbitrary images (as in a general-purpose computer display) or fixed images which can be displayed or hidden, such as preset words, digits, and 7-segment displays as in a digital clock. LCD has advantageous properties, such as thinner thickness, lighter weight, need for less driving voltage and also less consumption of electricity. However, because the LCD is non-light emitting diode which does not illuminate itself, the LCD needs a separate backlighting to supply light onto the LCD panel.
A backlight source such as cold cathode fluorescent lamp (CCFL) or light emitting diode (LED) is generally used for the LCD. The CCFL, which uses mercury, is slow in response, provides poor color representation, and may contribute to air pollution. Also, CCFL may not suitable for the LCD considering the demands for the LCD panel for thinner and smaller device.
In contrast, the LED does not use environmentally hazardous material and, thus, is environmentally friendly, and can be driven by impulse driving. In addition, LED provides good color representation, is capable of arbitrarily changing brightness, and color temperature by adjusting an amount of light of red, green, blue LEDs, and is suitable to achieve thinner and smaller LCD panels. Accordingly, LEDs have recently been widely employed as backlight sources of the LCD panels.
To connect the LCD backlight source to LED arrays consisting of a plurality of LEDs, a driving circuit is used to provide constant current to the respective LED arrays, and a dimming circuit is used to arbitrarily adjust brightness and color temperature or temperature compensation.